My first west marches game went great: IRL game, 2+yrs 'til COVID, about a dozen players, half of which were into the stronghold-building aspect.. and 2-3 players that played basically every session.Westmarches? Oh, hell yeah! I hope this helps get more CR fans interested to try more open-table style play.
My second and third attempts, online games (some with the same people that were IRL), fell flat. All of the players had played with me either online or in-person, but after a few sessions they really didn't like the idea that they were "missing out" on sessions that they didn't play in. Say group 1 goes to dungeon A, cleared 30% of it, had to leave at the end of the session. Group 2 goes to dungeon A, a week or two have passed so some stuff has changed etc, creatures moved in. They clear 60% of it. Group 1 went back to dungeon A, and were really annoyed that group 2 had been there, even if group 2's work led group 1 to clear the dungeon 100% on their return... and then group 2 would be annoyed that group 1 ended up clearing the place.